Breast cancer is the most prevalent cancer in women that frequently spreads and recurs, thus leading to high mortality. Despite advances in surgery and treatment, standard of care still relies primarily on chemo- and radiation therapies aimed at killing the tumor cells. Evolutionary models predict that selective pressure imposed by these approaches causes survival of resistant clones that eventually re-activate the disease. Based on the central involvement of metabolic tumor cell alterations in cancer, this application follows the hypothesis that therapeutic normalization of tumor cell metabolism can halt breast cancer progression and prevent relapse. If successful, this approach would not eradicate all residual disease, but rather achieve and maintain a disease symptom-free state. In principle, treatment aimed at normalizing tumor cell metabolism would not impose selective pressure, and thus not favor penetration of escaping clones to drive recurrence. If successful, therapeutic metabolic reprogramming could become a critical component of breast cancer care and have revolutionary impact on overall outcome by reducing the mortality in breast cancer. Having identified a cause-and-effect relationship between aberrant tumor cell mitochondrial complex I function, oncogenic growth, and metastatic progression in breast cancer, this information translated into a new strategy, where normalization of the NAD+/NADH redox balance through treatment with NAD precursors led to inhibition of tumor growth and metastatic disease in xenograft models and interference with breast cancer progression in an oncogene driven transgenic model of spontaneous breast cancer. Based on these findings, the proposed study seeks to 1. Evaluate the efficacy of NAD precursor treatment in xenograft and transgenic mouse models of breast cancer progression, including combination with standard of care; 2. Employ targeted metabolomics to define the tumor cell NAD+/NADH metabolome in defined stages of disease advancement and treatment using ESI QQQ and NIMS technology, combined with XCMS metabolomic bioinformatics; and 3. Generate untargeted comprehensive metabolic profiles of progressive stages in breast cancer. The outcome from our study may identify therapeutic normalization of tumor cell metabolism, e.g. through NAD precursor treatment, as an effective, non-toxic way to silence breast cancer and prevent recurrence. The metabolome of breast cancer progression will empower the field and enable development of preventive approaches based on the concept of metabolic normalization. Interactive and collaborative efforts using the information generated will help to reduce the mortality in breast cancer patients.